- From October 26, 2019, climbing Uluru, Australia’s famous desert rock, considered sacred by the local Anangu people, has been banned.
- The question is straightforward and aims to discuss Aeolian landforms in detail with special focus on Ayers rock as an example.
- In a short intro, define what Aeolian landforms are.
- In the start of the main body, explain the salient features of landforms created by wind.
- Discuss separately with diagrams different landforms such as pediplain, deflated hollows, Mushroom tables etc.
- Discuss specifically the features of Ayer’s rock and its significance.
- Conclude with the significance of wind-driven landform formations in physiography.
The wind is the main geomorphic agent in the hot deserts. Winds in hot deserts have greater speed which causes erosional and depositional activities in the desert. The landforms which are created by erosional and depositional activities of wind are called Aeolian Landforms. The wind or Aeolian erosion takes place in the following ways, viz. deflation, abrasion, and attrition. This process is not unique to the Earth, and it has been observed and studied on other planets, including Mars.
Erosional Landforms due to Wind:
- When the high relief structures in deserts are reduced to low featureless plains by the activities of wind, they are called Pediplains.
- Deflation Basins:
- Deflation is the removal of loose particles from the ground by the action of wind.
- When deflation causes a shallow depression by persistent movements of wind, they are called deflation hollows.
- A monadnock or inselberg is an isolated hill, knob, ridge, outcrop, or small mountain that rises abruptly from a gently sloping or virtually level surrounding plain.
- Mushroom Rocks:
- Ventifacts are rocks that have been abraded, pitted, etched, grooved, or polished by wind-driven sand or ice crystals.
- These geomorphic features are most typically found in arid environments where there is little vegetation to interfere with Aeolian particle transport, where there are frequently strong winds, and where there is a steady but not overwhelming supply of sand.
- Mushroom Tables / Mushroom rocks are Ventifacts in the shape of a mushroom.
- In deserts, a greater amount of sand and rock particles are transported close to the ground by the winds which cause more bottom erosion in overlying rocks than the top.
- This result in the formation of rock pillars shaped like a mushroom with narrow pillars with broad top surfaces.
- These are rock pillars which stand as resistant rocks above soft rocks as a result of differential erosion of hard and soft rocks.
- A table-shaped area of rock found in arid and semi-arid areas formed when more resistant rock is reduced at a slower rate than softer rocks around it.
- Ridge of rock, formed by the action of the wind, usually parallel to the prevailing wind direction.
- Wind bridges and windows:
- Powerful wind continuously abrades stone lattices, creating holes. Sometimes the holes are gradually widened to reach the other end of the rocks to create the effect of a window—thus forming a wind window. Window bridges are formed when the holes are further widened to form an arch-like feature.
Salient features of Ayers Rock:
- Uluru also known as Ayers Rock is a large sandstone rock formation in the southern part of the Northern Territory in central Australia. Uluru is listed as a UNESCO World Heritage Site.
- Scientists have estimated that Uluru is around 500 million years old, forming a similar time to when the Australian continent first developed. This all began when a large majority of Australia was underwater.
- The rock first began once the landmasses began to separate and move, causing two fans, one made of sand, and the other made of conglomerate rock, to be pushed together with force.
- Eventually, the pressure was so great the two fans condensing into one rock, to what we know today as Uluru.
- Southern Side
- The southern side of Uluru features a series of steep valleys with large pot-holes and plunge pools. This is all due to the continued water erosion on the arkose rock.
- From centuries of rainfall slowly cutting into the deep sections of Uluru until they eventually fell away with the stream, forming the large holes we see today.
- North-West Side
- Featured on Uluru’s north-west side is parallel ridges outlining the sedimentary layers of the rock. This is also caused by erosion, with large winds and rainfall cutting away segments.
- Uluru’s Smooth Surface
- The smooth sections of the red are all due to humans, with millions of feet travelling across the same section of rock every day.
- Uluru’s Flaky Surface
- The flaky exterior of Uluru is due to the chemical decay of the minerals present. Normally, the arkose rock is a greyish colour, however, the oxidation of the iron mineral present in the rock exposes a rusty flaky residue, causing the rust-red colour Uluru is famous for.
Thus, wind and water act as major erosional factors leading to the formation of various landforms.